[PATCH] D70643: [DebugInfo] Support for DW_OP_implicit_pointer (DW_OP_LLVM_implicit_pointer)

[Alok Kumar Sharma via Phabricator via llvm-commits]

alok updated this revision to Diff 232035.
alok marked an inline comment as done.
alok added a comment.

Update includes comments from @jmorse.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D70643/new/

https://reviews.llvm.org/D70643

Files:
  llvm/docs/LangRef.rst
  llvm/include/llvm/BinaryFormat/Dwarf.h
  llvm/lib/BinaryFormat/Dwarf.cpp
  llvm/lib/IR/AsmWriter.cpp
  llvm/lib/IR/DebugInfoMetadata.cpp


Index: llvm/lib/IR/DebugInfoMetadata.cpp
===================================================================
--- llvm/lib/IR/DebugInfoMetadata.cpp
+++ llvm/lib/IR/DebugInfoMetadata.cpp
@@ -837,6 +837,7 @@
   case dwarf::DW_OP_LLVM_convert:
   case dwarf::DW_OP_LLVM_fragment:
   case dwarf::DW_OP_bregx:
+  case dwarf::DW_OP_LLVM_implicit_pointer:
     return 3;
   case dwarf::DW_OP_constu:
   case dwarf::DW_OP_consts:
@@ -899,6 +900,13 @@
       return I->get() == expr_op_begin()->get() && I->getArg(0) == 1 &&
              getNumElements() == 2;
     }
+    case dwarf::DW_OP_LLVM_implicit_pointer: {
+      // A DW_OP_LLVM_implicit_pointer operator must appear at the beginning
+      // and it has two arguments, DW_OP_LLVM_arg0 and offset N.
+      return (I == expr_op_begin()) &&
+             (I->getArg(0) == dwarf::DW_OP_LLVM_arg0) &&
+             (getNumElements() == 3);
+    }
     case dwarf::DW_OP_LLVM_convert:
     case dwarf::DW_OP_LLVM_tag_offset:
     case dwarf::DW_OP_constu:
Index: llvm/lib/IR/AsmWriter.cpp
===================================================================
--- llvm/lib/IR/AsmWriter.cpp
+++ llvm/lib/IR/AsmWriter.cpp
@@ -2150,6 +2150,9 @@
       if (I->getOp() == dwarf::DW_OP_LLVM_convert) {
         Out << FS << I->getArg(0);
         Out << FS << dwarf::AttributeEncodingString(I->getArg(1));
+      } else if (I->getOp() == dwarf::DW_OP_LLVM_implicit_pointer) {
+        Out << FS << dwarf::OperationEncodingString(I->getArg(0));
+        Out << FS << I->getArg(1);
       } else {
         for (unsigned A = 0, AE = I->getNumArgs(); A != AE; ++A)
           Out << FS << I->getArg(A);
Index: llvm/lib/BinaryFormat/Dwarf.cpp
===================================================================
--- llvm/lib/BinaryFormat/Dwarf.cpp
+++ llvm/lib/BinaryFormat/Dwarf.cpp
@@ -167,6 +167,8 @@
     return "DW_OP_LLVM_arg6";
   case DW_OP_LLVM_arg7:
     return "DW_OP_LLVM_arg7";
+  case DW_OP_LLVM_implicit_pointer:
+    return "DW_OP_LLVM_implicit_pointer";
   }
 }
 
@@ -187,6 +189,7 @@
       .Case("DW_OP_LLVM_arg5", DW_OP_LLVM_arg5)
       .Case("DW_OP_LLVM_arg6", DW_OP_LLVM_arg6)
       .Case("DW_OP_LLVM_arg7", DW_OP_LLVM_arg7)
+      .Case("DW_OP_LLVM_implicit_pointer", DW_OP_LLVM_implicit_pointer)
       .Default(0);
 }
 
Index: llvm/include/llvm/BinaryFormat/Dwarf.h
===================================================================
--- llvm/include/llvm/BinaryFormat/Dwarf.h
+++ llvm/include/llvm/BinaryFormat/Dwarf.h
@@ -129,6 +129,7 @@
   DW_OP_LLVM_arg5 = 0x1009, ///< Only used in LLVM metadata.
   DW_OP_LLVM_arg6 = 0x100a, ///< Only used in LLVM metadata.
   DW_OP_LLVM_arg7 = 0x100b, ///< Only used in LLVM metadata.
+  DW_OP_LLVM_implicit_pointer = 0x100c, ///< Only used in LLVM metadata.
 };
 
 enum TypeKind : uint8_t {
Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -4821,6 +4821,10 @@
   metadata !DIExpression(DW_OP_LLVM_arg0, DW_OP_LLVM_arg1, DW_OP_plus))``
   ``DW_OP_LLVM_arg0`` represents ``DILocalVariable("x")`` and
   ``DW_OP_LLVM_arg1`` represents ``DILocalVariable("y")``.
+- ``DW_OP_LLVM_implicit_pointer, DW_OP_LLVM_arg0 N`` can only appear at the
+  beginning of a ``DIExpression``, and it specifies the value of variable
+  represented by the ``DILocalVariable`` referred to by the instructions 
+  value/address operand at offset N.
 
 DWARF specifies three kinds of simple location descriptions: Register, memory,
 and implicit location descriptions.  Note that a location description is


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